Name: Xheotris (Xe, for short) Longtail. In his youth, he was also known as "Little X".
Species: long-tailed weasel
Gender: (just so there's no confusion) male

Xe is a creature of many conflicts and more than a hint of mystery. His father, Zirrus was the head of "Xheotris Industries", and did not want his illegitimate offspring complicating his illicit operations. So he installed Xe and his sister Idria into a sinister program he was running at the time to develop super spies/assassins for various governments. The youngsters had a tracking chip embedded in their heads which was designed to kill or disable them should they go missing during a mission or attempt to turn against their training. This, of course, is exactly what "Little X" did.
By a strange coincidence, he came into contact with Twapa, and instantly developed an obsession with her. At one point he even attempted to kidnap her, but was foiled by X-I. He was punished for his disobedience, and for interfering and possibly ruining Zirrus' experiment he was conducting with Twap, and this resulted in Little X eventually turning against X-I and escaping from the facility where he had spent most of his life.
Of course, the tracking chip was activated, and, while he didn't die, Xe did temporarily lose his senses and wandered for some time before ending up on the doorstep of a kangaroo rat named Ciaran. Keer took him in and helped him recover from his delirium, but in spite of regaining his senses, Xe had completely lost all memory of his life at X-I or the things he had done.

By nature, Xe is a deeply thoughtful and even spiritual creature, and, when freed from the memory of his violent past, became an incredibly gentle and laid-back person. After learning the truth, Xe becomes increasingly conflicted, unsure of who he truly is: A ruthless killer, or a tender and loving friend? Which side will win out? Only time will tell.
First appearance.